It is known to direct a beam of electromagnetic radiation at a sample, optionally via a focusing means, such that said beam is focused onto a very small spot on said sample. It is further known to monitor a sequence of beam polarization states which are imposed on said beam and which are affected by interaction with said sample. Often said polarization states are mediated by application of a motor to effect continuous rotation, or stepped rotation of an element such as a polarizer, compensator or analyzer.
A problem which develops in very precise measurements is that vibrations caused by operation of said motor can affect the location on said sample where the beam impinges by altering the beam locus. In said very precise work the specific location on a sample where the focused beam impinges can affect how the polarization state of the beam is changed by interaction with said sample, and if the impingement position changes even a very small amount, the measurement results will not accurately represent the location it is intended to investigate. Further, undamped vibrations can have an effect on other components in a system.
A computer search for relevant patents has provided:                U.S. Pat. No. 6,935,201 to Abraham et al.;        U.S. Pat. No. 5,750,272 to Jardine;        U.S. Pat. No. 6,819,426 to Sezginer et al.;        U.S. Pat. No. 6,690,473 to Stanke et al.;        U.S. Pat. No. 6,829,054 to Stanke et al.;        U.S. Pat. No. 7,042,569 to Sezginer;        U.S. Pat. No. 7,173,699 to Xu et al.;        U.S. Pat. No. 7,196,328 to Kley;        U.S. Pat. No. 7,061,615 to Lowe-Webb;In addition Published Patent Applications:        No. US 2002/0158193 A1 by Sezginer et al.;        No. US 2004/0050189 A1 by Abraham et al.;        No. US 2004/0080757 A1 by Stanke et al.;        No. 2005/0018190 A1, by Sezginer et al.        
Need remains for a simple to apply system and method for damping vibrations in ellipsometer or the like systems.